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PeterDonis's latest activity
PeterDonis
replied to the thread
I
GPS system and general relativity
.
No. This statement is wrong. Yes, but... Yes, and in both cases I described, the effect of climbing out of other gravity wells (Sun...
49 minutes ago
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
Yes, as I said in this Insights article: https://www.physicsforums.com/insights/schwarzschild-geometry-part-2/
57 minutes ago
PeterDonis
replied to the thread
I
GPS system and general relativity
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This is not really correct. "SR" implies flat spacetime, and the spacetime in question is not flat. As I said in post #22, the correct...
Yesterday, 11:17 PM
PeterDonis
replied to the thread
I
GPS system and general relativity
.
It is a GR calculation for the GPS satellites in their particular orbits. For other satellites in other orbits, the correction will be...
Yesterday, 11:08 PM
PeterDonis
replied to the thread
I
GPS system and general relativity
.
Not really that long, since ECI coordinates do not rotate with the Earth. Navigators since forever or at least since it was known the...
Yesterday, 7:37 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
It does not have well-defined Schwarzschild coordinates at all. ##r = r_s## is on the horizon, so we cannot even say that it has...
Yesterday, 5:13 PM
PeterDonis
replied to the thread
I
GPS system and general relativity
.
Yes.
Yesterday, 4:05 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
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Not in a "set"--in a point of ##t##, ##r## space. (Or a single 2-sphere in the full spacetime.)
Yesterday, 3:51 PM
PeterDonis
replied to the thread
I
GPS system and general relativity
.
No. First, the 38 microseconds per day faster is for the "uncorrected" rates of the GPS clocks in their particular orbits. It says...
Yesterday, 3:10 PM
PeterDonis
replied to the thread
I
Phantom dark energy
.
He's not saying anything about whether dark energy is "created out of nowhere". He is taking some global numbers and describing them in...
Yesterday, 2:56 PM
PeterDonis
replied to the thread
I
Phantom dark energy
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What about it?
Yesterday, 2:45 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
If you insist on a one-to-one mapping of both coordinates, yes, that's true, because there is not a unique value of ##\theta## assigned...
Yesterday, 2:10 PM
PeterDonis
replied to the thread
I
Phantom dark energy
.
No. I'm saying that "energy being created" is a local concept--one that can't happen because it would violate the local conservation of...
Yesterday, 2:03 PM
PeterDonis
replied to the thread
I
Understanding the phrase "simultaneity convention"
.
Not really. In polar coordinates the metric coefficient ##g_{rr}## vanishes at ##r = 0##. That means the metric has a vanishing...
Yesterday, 12:14 PM
PeterDonis
replied to the thread
I
GPS system and general relativity
.
No, it's the overall blueshift, period. The +45 is the "gravitational" part and the -7 is the "motion" part. (Note that, as @JT Smith...
Yesterday, 10:48 AM
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